Medicament delivery device

ABSTRACT

A medicament delivery device includes a housing; a carrier for a medicament container, the carrier being slidable in the housing; a trigger unit; a cover unit coaxial and slidable in the housing; a release mechanism configured to be actuated partly by the trigger unit and partly by movement of the cover unit; a preloaded drive unit releasably connected to the carrier and controlled by the release mechanism for advancing the carrier to a predetermined proximal position in relation to the housing, the preloaded drive unit having a plunger rod and a helical drive spring disposed within the plunger rod, with at least one end of the helical drive spring configured to interact with an interior of the plunger rod; and a braking mechanism between the preloaded drive unit and the release mechanism configured to control a speed of the preloaded drive unit when advancing the slidable stopper within the container.

This application is a continuation-in-part of U.S. patent applicationSer. No. 13/806,779 filed on Dec. 23, 2012, which is a national-phase ofInternational Application PCT/SE2011/050775 filed on Jun. 17, 2011,which claims the benefit of the filing date of U.S. ProvisionalApplication 61/358,093 filed on Jun. 24, 2010, and which claims priorityfrom Swedish Application 1050692-1 filed on Jun. 24, 2010.

TECHNICAL AREA

This invention relates to a medicament delivery device comprising apreloaded drive unit for delivering a dose of medicament and moreparticularly to a braking mechanism for controlling the speed of thepreloaded drive unit.

BACKGROUND

There are many medicament delivery devices on the market that canperform a number of functions automatically.

One such medicament delivery device, disclosed in InternationalPublication WO 2005/044348, is capable of a penetration sequence, aninjection sequence, and thereafter a withdrawal sequence when a user hasactivated the device by first pressing it against an injection site andthereafter pressing an actuation button.

The device has been successful and is on the market for a number ofdifferent drugs for treatment of different diseases. The device uses adrive spring for both the penetration sequence as well as the subsequentinjection sequence. For some drugs, it is desirable that the spring isas weak as possible in order that the sequences shall not be performedtoo fast and at the same time ensure that the medicament container isproperly emptied, i.e., that the stopper is moved to the proximal endposition inside the medicament container. Even so, it has been foundthat the injection sequence preferably should be performed even slowerin order not to cause pain and discomfort to the user. There is thusroom for improvements of an otherwise well-functioning medicamentdelivery device.

SUMMARY

An object of the present invention is to remedy the drawbacks of thestate of the art devices. That object can be obtained by a medicamentdelivery device according to the features of the embodiments describedin this application.

According to one aspect of the invention, a medicament delivery deviceincludes an elongated housing; a carrier configured to house amedicament container to which a medicament delivery member is attached,where the carrier is slidably accommodated within the housing; a triggerunit having an actuator button and an actuator connected to each other;a cover unit coaxially and slidably disposed in the housing; a releasemechanism configured to be actuated partly by the operation of thetrigger unit and partly by movement of the cover unit; a preloaded driveunit releasably connected to the carrier and controlled by the releasemechanism for advancing the carrier to a predetermined proximal positionin relation to the housing, wherein the preloaded drive unit comprises aplunger rod and a helical drive spring disposed within the plunger rod;at least one end of the helical drive spring is configured to interactwith an interior of the plunger rod; and when the carrier reaches thepredetermined proximal position, the drive unit becomes disconnectedfrom the carrier for advancing a slidable stopper within the containerand thereby dispensing the medicament; and a braking mechanism betweenthe preloaded drive unit and the release mechanism configured to controla speed of the preloaded drive unit when advancing the slidable stopperwithin the container. The braking mechanism includes a helical groove onan outer surface of the plunger rod, and at least one inwardly directedprotrusion of the actuator interactively connected to the helical grooveby a non-positive connection such that advancement of the carrier to thepredetermined position causes rotation of the plunger rod. A windingdirection of the helical groove is opposite to a winding direction ofthe helical drive spring.

According to another aspect of the invention, the preloaded drive unitcomprises a drive spring and a plunger rod.

According to yet another aspect of the invention, the braking mechanismcomprises a first braking device on the outer surface of the plunger rodand a second braking device of the release mechanism interactivelyconnected to each other by a non-positive connection.

According to a further aspect of the invention, the trigger unitcomprises an actuator button and an actuator connected to each other.

According to yet a further aspect of the invention, the cover unitcomprises a delivery member cover and an actuator sleeve connected toeach other, wherein the actuator sleeve is coaxially and slidablyarranged on the actuator.

According to another aspect of the invention, the release mechanismcomprises annular inwardly directed ledges on flexible tongues of theactuator, and recesses on the outer surface of the plunger rod arrangedto be engaged with each other for holding the drive unit in a preloadedstate in which the drive unit is connected to the carrier by a carrierdriver.

According to yet another aspect of the invention, the first brakingdevice is at least one groove on the outer surface of the plunger rodand wherein the second braking device is at least one inwardly directedprotrusion on the flexible tongues of the actuator.

According to a further aspect of the invention, the at least one groovecomprise a number of sections forming a zig-zag shape.

According to yet a further aspect of the invention, the at least onegroove has a helical extension around the plunger rod.

According to another aspect of the invention, the at least one groovehas a pitch that can be modified during manufacturing for modifying thespeed of the plunger rod.

According to yet another aspect of the invention, a section of the atleast one groove at the proximal end of the plunger rod has a directiongenerally parallel with the longitudinal direction of the plunger rod.

According to yet another aspect of the invention, at least one end ofthe helical drive spring includes a tang that interacts with theinterior of the plunger rod such that when the plunger rod rotates, thetang contacts the interior of the plunger rod. Each end of the helicaldrive spring can also include a respective tang.

There are several advantages with the present invention. Because of theplunger rod brake it is possible to use stronger drive springs withoutthe drawback that the dose delivery is performed very fast, whichotherwise would be the case with stronger drive springs. Thereby it isascertained that the medicament container is properly emptied.

Further the control of the speed of the plunger rod is acting directlyon the plunger rod by the at least one protrusion acting in the at leastone groove. Thus a very efficient yet simple design is obtained. It isalso rather easy to change the speed of the plunger rod by altering thepitch of the at least one groove. Since the force of the drive spring islow at the end of the injection sequence no braking action is needed andthus the most proximal groove section is preferably generally parallelwith the extension of the plunger rod.

These and other aspects and advantages of the present invention willbecome apparent from the following detailed description of the inventionand from the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be understood by reading this description inconjunction with the drawings, in which:

FIGS. 1A, 1B, 1C are cross-sectional views of a medicament deliverydevice according to the present invention,

FIG. 2 is an exploded view of a proximal part of the device of FIG. 1,

FIG. 3 is an exploded view of a distal part of the device of FIG. 1,

FIG. 4 is a cross-sectional view of the distal part of the device ofFIG. 1,

FIG. 5 is a detailed view of one embodiment of the braking mechanism,

FIG. 6 is a detailed view of another embodiment of the brakingmechanism, and

FIG. 7 is a detailed view of yet another embodiment of the brakingmechanism.

DETAILED DESCRIPTION

In this application, the term “distal part/end” refers to the part/endof a medicament delivery device, or the parts/ends of the membersthereof, which under use of the medicament delivery device is locatedfarthest away from the medicament delivery site of the patient.Correspondingly, the term “proximal part/end” refers to the part/end ofa medicament delivery device, or the parts/ends of the members thereof,which under use of the medicament delivery device is located closest tothe medicament delivery site of the patient.

According to an aspect of the invention, the medicament delivery devicecomprises an elongated housing; a medicament container carrier 36adapted to house a medicament container 16 to which a medicamentdelivery member is attached and wherein the carrier is slidablyaccommodated within the housing; a trigger unit; a cover unit coaxiallyand slidably arranged within the housing; a release mechanism adapted tobe partly actuated by the operation of the trigger unit and partlyactuated by the movement of the cover unit; a preloaded drive unitreleasably connected to the medicament container carrier and controlledby the release mechanism for advancing firstly the medicament containercarrier to a predetermined proximal position in relation to the housingand upon the carrier reaching the predetermined proximal position, thedrive unit becomes disconnected from the carrier for advancing aslidable stopper within the container and thereby dispensing themedicament; and a braking mechanism acting between the preloaded driveunit and the release mechanism for controlling the speed of thepreloaded drive unit when advancing the slidable stopper within thecontainer.

The preloaded drive unit comprises a drive spring 64 and a plunger rod60. The braking mechanism comprises a first braking device on the outersurface of the plunger rod and a second braking device of the releasemechanism interactively connected to each other by a non-positiveconnection. The trigger unit comprises an actuator button 102 and anactuator 80 connected to each other. The cover unit comprises a deliverymember cover 20 and an actuator sleeve 110 connected to each other,wherein the actuator sleeve is coaxially and slidably arranged on theactuator 80. The release mechanism comprises annular inwardly directedledges 86 on flexible tongues 90 of the actuator 80, and recesses 62 onthe outer surface of the plunger rod 60 arranged to be engaged with eachother for holding the drive unit in a preloaded state in which the driveunit is connected to the carrier by a carrier driver 68.

FIGS. 1-6 show exemplary embodiments of a medicament delivery deviceaccording to the present invention.

The device shown in FIG. 1 comprises an elongated housing formed by agenerally tubular proximal housing 12 and a distal housing 124 of agenerally tubular shape, but not restricted to it. The proximal housingcomprises elongated openings 14 for viewing a medicament container 16,FIG. 1, and a somewhat narrowing proximal end.

The shown medicament container 16 is a syringe with a medicamentdelivery member in the form of an integrated injection needle. It ishowever to be understood that other types of medicament containers maybe employed within the scope of the present invention as well as othertypes of medicament delivery members such as mouth or nose pieces,nozzles, nebulizers and the like.

The distal end of the proximal housing 12 is arranged with annularrecesses 18 on the inner surface. The proximal end of the distal housinghas a somewhat lesser outer diameter, corresponding to the innerdiameter of the distal end of the proximal housing and provided with anumber of annular protrusions 126 which are intended to fit into thecorresponding annular recesses 18 on the inner surface of the proximalhousing 12. Inside the elongated housing the cover unit is slidablyarranged. The delivery member cover 20 is generally tubular with a firstproximal part 22 having a certain diameter and a second distal part 24having a diameter larger than the proximal part 22, where these partsare joined by an intermediate conical part 26, FIG. 2. Two oppositeelongated grooves 28 are arranged along the delivery member cover forviewing the medicament container. On the inner surface of the conicalpart a circumferential ledge 30 is arranged. At the circumferentialdistal end of the delivery member cover two openings 32 are arrangedopposite each other, where each opening is arranged with somewhatinwardly projecting, flexible, tongues 34.

Further, the medicament container carrier 36 is arranged inside thedelivery member cover in the form of a generally tubular body. Theproximal part of the medicament container carrier 36 is arranged with aneck portion 38 of lesser diameter. Adjacent the neck portion cut-outs40 have been made on either side to form guide surfaces. These surfacescooperate with corresponding shapes of the inner surface of the deliverymember cover 20 in order to obtain a stop device against rotation of themedicament container carrier 36 relative the delivery member cover. Thedistal end of the medicament container carrier is arranged with twodistally directed tongues 42 where each tongue is arranged with anopening 44 and an inwardly directed ledge 46 on the distal edge of eachopening. The medicament container carrier is further arranged withradially directed flanges 48 on its inner surface in order to obtain aspace between the medicament container carrier inner wall and themedicament container to be placed inside.

At the proximal end of the proximal part of the delivery member cover, aneedle protection cap grabber 50 is arranged. It is inserted into theproximal part of the delivery member cover and held there by friction.Inside the cap grabber a metal ring 52 is arranged with sharp pointedtongues 54 directed somewhat inwards and towards the proximal end.

FIGS. 3-4 show a distal part of the device according to FIG. 1. FIG. 3shows the plunger rod 60 formed as a tube and with an outer diametersomewhat smaller than the inner diameter of the medicament container tobe used. The recesses 62 of the plunger rod 60 comprise a certain widthand depth. Inside the plunger rod 60 is arranged the drive spring 64 ase.g. a helical compression spring. Adjacent the recesses 62 of theplunger rod 60, the carrier driver 68 is arranged. The carrier drivercomprises a tubularly shaped body 70 with an annular ledge 72 and anumber of flexible tongues 74 directed towards the distal end of thedevice, FIG. 3. Each tongue 74 is arranged with inwardly directed ledges76, FIG. 4, arranged and shaped as to fit into the recesses 62 of theplunger rod 60. Further, the ledges 46 of the medicament containercarrier 36 pass behind the annular ledge 72 of the carrier driver 68such that the container carrier and the carrier driver are connected toeach other

As seen in FIG. 4, the actuator 80 with a mainly tubular shape iscoaxially arranged surrounding the plunger rod 60. A number oflongitudinally directed cut-outs 88 are arranged at the proximal part ofthe actuator so as to form flexible tongues 90, FIGS. 3-5. The proximalend of each flexible tongue 90 has an inclined transition surface 82which meets with a band-shaped part 84 with enlarged diameter. On theinner surface adjacent each transition surface 82, the annular inwardlydirected ledge 86 is arranged, with a shape as to fit into the recesses62 of the plunger rod 60. The actuator 80 is further provided with twostop ledges 92 directed radially outwards from the outer surface oneither side, FIG. 5. Between the stop ledges two flexible tongues 94 arearranged on the outer surface. Each tongue is arranged with an outwardlydirected hook 96 at the outer end and a protrusion 98, with an inclinedsurface 99, a distance along each tongue, FIG. 4. On the innercircumferential surface of the distal housing, an annular ring 128 isarranged, which ring is provided with a circumferential ledge 130 with ashape corresponding to the hooks 96 of the actuator. The upper end ofthe actuator is arranged with a transversal end wall 100. The actuatorbutton 102 is attached to the upper end of the actuator having twotongues 104 attached and directed in the proximal direction of thedevice, forming the trigger unit.

The actuator sleeve 110 is coaxially and slidably arranged on theactuator 80. As seen in FIG. 3, the actuator sleeve 110 comprises aproximal end with a conical part 112 ending in a ledge 114 on its outersurface. At a distance from the ledge 114, a first annular ring 116 isarranged the outer surface. A second annular ring 118 is also arranged afurther distance from the ledge 114. The distal end of the actuatorsleeve is arranged with two oppositely arranged cut-outs 120 of agenerally rectangular shape where the widths correspond to the width ofthe stop ledges 92 of the actuator. A compression spring 122, FIG. 1 a,hereafter named delivery member cover spring surrounds the actuatorsleeve 110 and is arranged between the second annular ring 118 of theactuator sleeve and the annular ring 128 on the inner surface of thedistal housing. At the circumferential distal end of the delivery membercover two openings 32 are arranged opposite each other, where eachopening is arranged with somewhat inwardly projecting tongues. Theflexible tongues 34 at the openings 32 of the delivery member cover fitinto the circumferential recess formed between the first 116 and thesecond 118 annular rings of the actuator sleeve, such that the deliverymember cover and the actuator sleeve form the cover unit.

According to the invention, the first braking device is at least onegroove on the outer surface of the plunger rod and the second brakingdevice is at least one inwardly directed protrusion on the flexibletongues 90 of the actuator 80.

According to a first embodiment, the first braking device is at leastone groove 123 on the outer surface of the plunger rod 60 withalternating groove sections with inclined directions in relation to thelongitudinal direction of the plunger rod, i.e. forming a kind ofzig-zag pattern, FIG. 5. Further, according the first embodiment, thesecond braking device is at least one inwardly directed protrusion 125on the oppositely positioned tongues 90. The at least one inwardlydirected protrusion 125 has a shape which fits into the at least onegroove 123 of the plunger rod. The at least one groove 123 has a pitchthat can be modified during manufacturing for modifying the speed of theplunger rod.

According to a second embodiment, the first braking device is at leastone groove 140 made as a helically extending groove on the outer surfaceof the plunger rod, FIG. 6. As with the previous embodiment, the secondbraking device is at least one inwardly directed protrusion 142 on theoppositely positioned tongues 90. When the plunger rod now moves in theproximal direction during medicament delivery, the protrusions 142 slidealong the side surfaces of the helically extending groove 140 and due tothe friction, the speed of the plunger rod is lowered. As with theprevious embodiment, the speed can be changed by changing the pitch ofthe helical groove 140 in relation to the longitudinal direction.

Further, the at least one groove 123 of the first embodiment and thehelically extending groove 140 of the second embodiment have, at thedistal end of the plunger rod, a groove section 123 a with a directiongenerally corresponding with the longitudinal direction of the plungerrod, the function of which will be described below.

The plunger rod 60 is held against the force of the compression springby the release mechanism wherein the inwardly directed ledges 86 of thetongues 90 of the actuator are situated in the recesses 62 of theplunger rod 60 and that the actuator sleeve 110 prevents the tongues 90from moving radially outwards. Further the ledges 76 of the carrierdriver are also arranged into the recesses 62. The hooks 96 of theactuator 80 are adjacent the circumferential ledge 130 as a secondsafety device.

When a medicament delivery is to be performed the needle protection capgrabber is pulled out of the device. If the actuator button isdepressed, without having depressed the cover unit against a deliverysite, the hooks 96 of the actuator 80 will be engaged with thecircumferential ledge 130 of the distal housing, and will therebyprevent the inwardly directed ledges 86 of the tongues 90 of theactuator from being released from the recesses 62. However, when theproximal end of the cover unit is pressed against a dose delivery siteagainst the force of the compression spring 122, the distal end of thedelivery member cover is in contact with the first annular ring 116 ofthe actuator sleeve 110 and its movement causes the sleeve to move inthe distal direction, whereby a part of the proximal end of theband-shaped part 84 is moved outside the proximal end of the actuatorsleeve 110. The distally directed edge of the actuator sleeve 110 willthen come in contact with the inclined surface 99 of the tongues 94 onthe actuator 80 whereby the hooks 96 are moved radially inwards and arefree to pass longitudinally inside the circumferential ledge 130.

The next step is to activate the penetration and dose delivery. Shouldthe user however remove the device from the delivery site thecompression spring 122 will push the actuator sleeve 110 and thereby thedelivery member cover 20 back to its original position and a press onthe button will not cause the device to fire. When activating thepenetration and dose delivery, the user merely depresses the actuatorbutton 102. This causes the actuator to be moved in the proximaldirection whereby the hooks 96 pass inside the circumferential ledge 130and the band-shaped part 84 moves completely out of the actuator sleeve.The resilient properties of the flexible tongues 90 of the actuatorcauses the ledges 86 to move out of the groove 62 of the plunger, whichthen is free to move due to the preloaded spring 64. The penetrationstops when the proximal surface of the medicament container carrier 36abuts the circumferential ledge 30 of the delivery member cover and theledges 76 of the carrier driver 68 are also moved out of the groove 62because the arms 74 of the carrier driver are no longer held in place bythe band-shaped part of the actuator. I.e. the plunger rod isdisconnected from the container carrier and starts to act on thestopper.

However the speed of the plunger rod in the proximal direction isaffected by the first and second braking devices due to the frictionbetween the protrusions 125 and the side walls of the groove 123 of theplunger rod 60. In this context it is to be understood that the frictionforce and thus the speed can be modified by changing the pitch of thegroove section in relation to the longitudinal direction.

The force from the compression spring 64 now moves the stopper insidethe medicament container 16 and the liquid medicament is delivered tothe patient until the stopper reaches the inner proximal end of themedicament container 16, still under the influence of the first and thesecond braking devices. However, preferably the most proximal grooveportion 123 a is generally in line with the longitudinal direction ofthe plunger rod, i.e. there is no braking action at the end of the dosedelivery sequence and this is due to that the force of the drive springdecreases when it is expanding during penetration and subsequent dosedelivery such that the force at the end of the dose delivery sequence isso low that no braking action is necessary.

When the plunger rod 60 has moved the stopper to the proximal end of themedicament container, its distal end has passed the ledges 86 of theactuator 80 and the tongues 90 are moved inwards. Because thecompression spring 64 is also acting on the actuator 80, the actuator 80is moved inside the actuator sleeve 110. Because of this and because thedelivery member cover spring 122 is acting on the actuator sleeve 110 itis urged in the proximal direction. When now the device is removed fromthe medicament delivery site, the force of the delivery member coverspring 122 pushes the actuator sleeve 110 and thus the delivery membercover 20 connected to it in the proximal direction, whereby the deliverymember cover 20 is pushed out of the proximal end of the device andsurrounds the medicament delivery member. The movement of the actuatorsleeve causes the band-shaped part 84 of the actuator 80 to pass ribsarranged on the inner surface of the actuator sleeve. These ribs preventany attempts to push the delivery member cover back into the devicebecause the ribs will abut the proximal end of the band-shaped part 84of the actuator 80. The delivery member cover is thus locked.

A third embodiment of the invention is depicted in FIG. 7. In the thirdembodiment, which is similar to the second embodiment depicted in FIG.6, the braking mechanism includes a helically extending groove 140′ onthe outer surface of the plunger rod 60 and at least one inwardlydirected protrusion 142 on the oppositely positioned tongues 90 of theactuator 80. In addition, the helically extending groove 140′ is formedwith a winding direction, i.e., either clockwise or counterclockwise,that is opposite to the winding direction of the helical drive spring 64that can be disposed inside the plunger rod 60 as described above anddepicted in FIG. 7.

When the plunger rod 60 moves in the proximal direction duringmedicament delivery, the plunger rod rotates and the at least oneinwardly directed protrusion 142 (see FIG. 6) slides along the sidesurfaces of the helically extending groove 140′ and due to the friction,the speed of the plunger rod is lowered. As with previously describedembodiments, the speed can be changed by changing the pitch of thehelically extending groove 140′ in relation to the longitudinaldirection. In addition, by winding the helically extending groove 140′in the opposite direction of the drive spring 64, the plunger rod 60interacts with the spring 64.

A way the rod interacts with the spring is through a sharp edge or tang65, 65′ included on at least one of the lowest, or most proximal, coilof the spring 64 and the highest, or least proximal, coil of the spring64. The tang 65′ is indicated by a dashed line as it is hidden in FIG.7. The spring and at least one tang are such that when the plunger rod60 rotates, at least one of an area at or near the bottom, or mostproximal, inner wall of the plunger rod and an area at or near the top,or least proximal, inner wall of the plunger rod contacts a sharp edgeor tang of the spring 64. A result of the contact or contacts is thatthe edge or tang 65, 65′ digs into or grips the plunger rod 60, whichmay be made of plastic, thereby effectively slowing down the rotation ofthe plunger rod. It is currently believed that it is preferable that thespring 64 generally should have sharp edges at both its ends and shouldnot otherwise touch the interior wall of the plunger rod 60, leavingsome clearance between them, except for possible minor contact, such asdue to buckling of the spring.

Further as with the first and second embodiments, the helicallyextending groove 140′ can have, at the distal end of the plunger rod 60,a groove section 123 a with a direction generally corresponding with thelongitudinal direction of the plunger rod 60.

It is to be understood that the embodiments described above and shown inthe drawings is to be regarded only as a non-limiting example of theinvention and that it may be modified in many ways within the scope ofthe patent claims.

What is claimed is:
 1. A medicament delivery device, comprising: anelongated housing; a carrier configured to house a medicament containerto which a medicament delivery member is attached, wherein the carrieris slidably accommodated within the housing; a trigger unit, comprisingan actuator button and an actuator connected to each other; a cover unitcoaxially and slidably disposed in the housing; a release mechanismconfigured to be actuated partly by the operation of the trigger unitand partly by movement of the cover unit; a preloaded drive unitreleasably connected to the carrier and controlled by the releasemechanism for advancing the carrier to a predetermined proximal positionin relation to the housing, wherein the preloaded drive unit comprises aplunger rod and a helical drive spring disposed within the plunger rod;at least one end of the helical drive spring is configured to interactwith an interior of the plunger rod; and when the carrier reaches thepredetermined proximal position, the drive unit becomes disconnectedfrom the carrier for advancing a slidable stopper within the containerand thereby dispensing the medicament; and a braking mechanism betweenthe preloaded drive unit and the release mechanism configured to controla speed of the preloaded drive unit when advancing the slidable stopperwithin the container, wherein the braking mechanism comprises: a helicalgroove on an outer surface of the plunger rod; and at least one inwardlydirected protrusion of the actuator interactively connected to thehelical groove by a non-positive connection such that advancement of thecarrier to the predetermined position causes rotation of the plungerrod; wherein a winding direction of the helical groove is opposite to awinding direction of the helical drive spring.
 2. The medicamentdelivery device of claim 1, wherein the cover unit comprises a deliverymember cover and an actuator sleeve connected to each other, and theactuator sleeve is coaxially and slidably arranged on the actuator. 3.The medicament delivery device of claim 2, wherein the release mechanismcomprises annular inwardly directed ledges on flexible tongues of theactuator and recesses on the outer surface of the plunger rod configuredto engage each other for holding the drive unit in a preloaded state, inwhich the drive unit is connected to the carrier by a carrier driver. 4.The medicament delivery device of claim 3, wherein the at least oneinwardly directed protrusion is disposed on the flexible tongues of theactuator.
 5. The medicament delivery device of claim 1, wherein thehelical groove has a pitch that when modified during manufacturingmodifies a rotation speed of the plunger rod.
 6. The medicament deliverydevice of claim 5, wherein a section of the helical groove at a proximalend of the plunger rod has a direction that is generally parallel with alongitudinal direction of the plunger rod.
 7. The medicament deliverydevice of claim 1, wherein the at least one end of the helical drivespring includes a tang that interacts with the interior of the plungerrod such that when the plunger rod rotates, the tang contacts theinterior of the plunger rod.
 8. The medicament delivery device of claim7, wherein each end of the helical drive spring includes a respectivetang.